Conventionally, a switched capacitor circuit having an operational amplifier is known as an amplifier circuit to amplify an analog signal by a predetermined gain. In such an amplifier circuit, virtual ground voltage approaches an ideal value as the gain of the operational amplifier becomes larger, which leads to the improvement of amplification accuracy. However, in recent years, the development of miniaturization of CMOS devices has made it difficult to design an operational amplifier having a high gain. This leads to a problem that a large amplification error occurs in the above conventional amplifier circuit.
Further, an amplifier circuit having a comparator instead of the operational amplifier has been proposed. However, an amplification error depending on the finite delay of the comparator occurs in this amplifier circuit. This leads to a problem that power consumption has to be considerably increased to make the amplification error small.